Method of supporting the shell section of a blast furnace



Dec. 24, 1968 AKIO KISHIMOTO ET AL 3,417,955

METHOD OF SUPPORTING THE SHELL SECTION OF A BLAST FURNACE Filed Oct. 24. 1966 3 Sheets-Sheet 1 FIG. I

SUPPORTING PORTION I2 d STRESS AT AN ARBITRARY POINT 4, =REFERENCE STRESS l o 20 40 60 so DISTANCE FROM THE CENTER OF A SUPPORTING PORTION IN A CIRCUMFERENTIAL DIRECTION (mm) INYHNRS AKIO KISIIINOTO Rama .4 I ONPAHA Dec. 24, 1968 AKK) s mo-ro ET AL $417,955

METHOD OF SUPPORTING THE SHELL SECTION OF A BLAST FURNACE Filed Oct. 24. 1966 5 Sheets-Sheet 2 iE-Ei luvzumu Ame KISHmoro mmmu on-mvA Dec. 24, 1968 AKlo KI SHIMOTO ET AL 3,'fi7,9 55

METHOD OF SUPPORTING THE SHELL SECTION OF A BLAST FURNACE Filed Oct. 24, 1966 3 Sheets-Sheet 5 FIG. 5

FIG. 6

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United States Patent 3,417,955 METHOD OF SUPPORTING THE SHELL SECTION OF A BLAST FURNACE Alrio Kishimoto, Hiroshima-ken, and Kimiaki Ohtawa, Hiroshima-shi, Japan, assignors to Mitsubishi Jukogyo Kabushilri Kaisha, Tokyo, Japan Filed Oct. 24, 1966, Ser. No. 589,027 Claims priority, application Japan, Oct. 26, 1965, 40/ 65,658 6 Claims. (Cl. 248-351) ABSTRACT OF THE DISCLOSURE A method of supporting the shell sections of a blast furnace includes using at least three pole braces or columns each of which carries a plurality of fiat circumferentially widened supporting plates which are spaced apart by an amount suflicient to insure that their respective supporting influences on the shell of the blast furnace are independent from one another and they are separated to provide a plurality of unsupported cooling areas beneath the shell. In a preferred arrangement for a blast furnace having an output of 2600 tons per day, the pole braces are constructed in a number and arrangement to provide supporting plates at intervals at 3000 mm., a distance which insures that the support of each plate does not interfere with the next adjacent plate. Each pole brace or column advantageously carries two supporting plates arranged adjacent each end of an upper cross member in the configuration of a T.

Summary of the invention The present invention relates to a method of supporting the shell section of a blast furnace of so-called steel frame and shell-type wherein the load of top members such as turning charging apparatus is carried by four steel frame poles while the load of the furnace body i.e. the shell section is carried by plural poles or columns which are arranged around the bottom, or of shell-type wherein the load of top members is carried by the shell which is supported by plural poles or columns which are arranged around the bottom.

The number of the poles which support the shell in the blast furnace of steel frameand shell-type or of shelltype has been determined in due consideration of the strength of the shell as well as the load to be borne by the shell section so that the shell may not be broken. Their number is usually six in a small blast furnace and eight in a large blast furnace at the values of a strength of the shell and a load to be borne by the shell section which have been adopted hitherto.

However, the fact that there are six or eight pole braces around the furnace bottom does not permit of sufficient space for tap hole opening machines and tap hole closing machines even in the present blast furnace, and complicates the circumference of its hearth section under the present conditions that there is a tendency to require twenty eight to thirty tuyeres in order to improve the efficiency of the furnace while twenty four tuyeres at the most were required for a furnace in the past and this results in the reduced working efficiency in the circumference of the hearth which in its turn decreased the efficiency of iron works as a whole.

On the other hand, a blast furnace shows a tendency toward a larger size with an increasing demand for iron and steel and this necessitates an increase in size of its shell. Since there is a limit to the thickness of steel plates, the strength of the shell may not be increased in proportion to an increase in its size. The increased load of the shell section to be accompanied by increased size of a blast furnace would require the increased number of pole braces or columns and have influence on the working efficiency in the circumference of the hearth.

It is a principal object of the invention to reduce the number of the poles which carry the load of the shell section and then to improve the working efficiency in the circumference of the hearth.

The invention will be explained in connection with the accompanying drawings, in which:

FIG. 1 is a diagram showing the stress distribution in a shell in the vicinity of supporting portion thereof;

FIG. 2 is a schematic sectional elevational view of a blast furnace embodying the invention;

FIG. 3 is a sectional plan view taken along the line IIIIII of FIG. 2;

FIG. 4 is a front view of a pole brace;

FIG. 5 is a side view of the pole brace; and

FIG. 6 is a sectional plane view taken along the line VIVI of FIG. 5.

The number of pole braces for supporting the shell section of a blast furnace is determined by the load of the shell section and the strength of the shell, but those pole braces cannot be arranged unconditionally around the furnace. For example, two of those poles, when standing very close to each other, serve merely as one pole, and if all the poles are designed to bear the load equally, an other poles will have to bear, while the shell will be burdened over a determined value of it so that the problem of strength will arise. In the past those pole braces were arranged at regular intervals around the furnace.

We made a test on a model of a blast furnace having about 1,700 m. in furnace volume (iron output: 2,600 t./d.) which is reduced to a scale of one-thirtieth of the actual size, and obtained the result as shown in FIG. 1 wherein the influence of a pole brace on the shell is plotted as a 0/0 curve (0'; stress at an arbitrary point, 0' reference stress). As is clear from the curve showing the stress distribution, the stress intensity of the shell, marked with a negative sign because of being compres sion stress, increases slightly at the point in the immediate vicinity of a supporting portion, but decreases gradually with the distance from the center of the supporting portion in a circumferential direction of the shell. And the above influence is never recognized at the point which is 50 mm. from the center. In other words, one supporting portion exerts the influence in strength on the shell in each range of 50 mm. in both circumferential direction of its center, namely, in a total range of mm. Accordingly, in case of this test the respective supporting portions, when provided at intervals of about 100 mm., will not interfere with one another and carry fully the loads allotted to them as independent supporting portions.

As is understood from the above result, pole braces in an actual blast furnace having iron output of 2,600 t./d., when provided at intervals of 3,000 mm. (100 mm. 30) in consideration that the model is on the scale of onethirtieth, may serve as independent pole braces of one another in the same ways as in the model without interference with ane another concerning the load of the shell to be allotted to them.

In case eight pole braces are used for carrying the load of the shell, it is clear that, though every other pole brace is so displaced in a same circumferential direction as to approach to a position 3,000 mm. apart from every remaining pole brace, the load to be bourne actually by each of the pole braces as well as the influence in strength of each on the shell remains unchanged. The distance of 3,000 mm. between thus approached pole braces is not so large in comparison with one-eighth of the circumferential length of the furnace bottom section.

Referring now to FIGS. 2 to 6, the furnace body 1 of a blast furnace is provided with a charging apparatus 2 at its top. The load of the furnace body 1 is carried by the shell 3. At the lower end of the shell 3 there is arranged an annular plate 4 through which plural pole braces 5 support the shell 3. In this case four pole braces 5 are provided at regular intervals around the furnace bottom. Each of the pole braces 5 has an enlarged portion 6 made of a steel which is welded to its top. On the upper surface of the portion 6 there are mounted two steel plates 7 which come into contact with the annular plate 4 so as to carry the load of the shell section. The distance between the centers of both steel plates 7 in a blast furnace having iron output of 2,600 t./d. is set to about 3,000 mm. The load of the shell 3 transmitted to each pole brace 5 through two steel plates 7 on its top. In transmission of the load of the shell 3 to each pole brace 5, two steel plates 7 receive a predetermined share of the load while the pole brace bears the load received by said two steel plates. The steel plates 7 act each as an independent supporting point so that their influences on the shell are also independent of one another. Consequently four pole braces may produce the effect of eight poles.

The pole brace according to the invention requires a material in quantity slightly more than the prior pole brace, but its size does not increase so much, although it produces the eifect of two poles. As a result a relative large free space may remain around the furnace bottom, and this makes it possible to improve largely the working efficiency in the circumference of the hearth section.

Though the distance between two steel plates 7 on the pole brace may be increased so far as the steel plates exert the influences on the shell independently of each other, a rational design capable of lending beauty to it is preferably required, since the excess distance not only requires much material for it but is uneconomical.

What is claimed is:

'1. A support for a blast furnace having an annular supporting flange, comprising at least three upright pole braces of substantially T-shaped configuration anchored at their lower ends and having upper ends engaged beneath the supporting flange of the blast furnace, at least the upper ends of said braces being elongated in circumferential directions below and in alignment with the blast furnace flange and presenting a plurality of raised flat circumferentially elongated supporting portions engaged with the blast furnace supporting flange and supporting the blast furnace at a plurality of separate locations spaced apart by an amount to provide cooling ventilation between adjacent supporting portions and stress independent load bearing support by each said portion.

2. A support according to claim 1, wherein said blast furnace has an output of 2600 tons per day and wherein said supporting portions are spaced apart by approximately a distance of 3000 mm.

3. A support according to claim 2, wherein there are eight equally spaced pole braces around the periphery of said shell.

4. A support according to claim 1, wherein said braces include a vertically elongated pole portion, an enlarged portion extending outwardly from each side adjacent the upper end of said pole portion in a symmetrical form, and a steel bearing plate carried on the top at each side of said enlarged portion.

5. A support for a blast furnace according to claim 4, wherein said enlarged portion includes a portion extending inwardly from said brace supporting a portion of said plates.

6. A method of supporting the shell sections of a blast furnace comprising arranging a plurality of substantially T-shaped supporting columns beneath the shell section of the furnace at equally spaced locations around the supporting shell section rim and providing contact bearing supports between the shell section and the supporting columns with plates which are spaced apart by an amount suflicient to insure that their respective supporting influences and local bearing support on the shell are independent of one another.

References Cited 915,483 1/1963 Great Britain.

ROY D. FRAZIER, Primary Examiner.

FRANK DOMOTER, Assistant Examiner.

US. Cl. X.R. 

